De Leo, R Argentieri, A G Bellunato, T Calvi, M Cisbani, E Cusanno, F Garibaldi, F Lagamba, L Marra, M Marrone, S Matteuzzi, C Musico, P Nappi, E Perego, D L Torrioli, S Vilardi, I Nucl. Instrum. Methods Phys. Res., A 10.1016/j.nima.2009.06.084 381-383 617 1-3 2010 2010 The performance of a proximity focusing Ring Imaging Cherenkov detector equipped with a radiator of silica aerogel is presented. The aerogel tile used is a monolith with variable index of refraction. Cherenkov photons are detected with high granularity by eight Hamamatsu H9500 flat panel multi anode phototubes.